A female doctor will be punished for having a sexual relationship with a highly vulnerable "much younger man", who tried to commit suicide when she ended it.

The 40-year-old general practitioner sent her 20-year-old patient explicit text messages for more than a year, and was once caught "spending time" with him in the back of a parked car, according to a Health Practitioners Disciplinary Tribunal ruling released yesterday.

The doctor also encouraged the young man to delete emails and messages between the two, which the tribunal believed was to hide evidence of her misconduct.

It said the end of the relationship between "Dr M" and "Mr X", who both have permanent name suppression, was "devastating" for the young man. "His health and ability to function deteriorated; he had multiple suicide attempts, and prolonged admissions to hospital and mental health institutions."

"Such an outcome could have been predicted and provides a clear illustration of why relationships between doctors and former patients (in particular, former patients who are known to be vulnerable) are prohibited."

The November decision, from the Professional Conduct Committee, detailed how Mr X first became a patient of Dr M in August 2009 when he was 19-years-old.

Mr X had multiple problems including heavy binge drinking, attempted suicides and involvement with community drug and alcohol services.

Dr M and Mr X quickly grew close, with Mr X's mother saying in March 2010 that she was "embarrassed" by their intimacy. They saw each other every week, and Mr X occasionally babysat the doctor's children.

Around the middle of 2010, Dr M referred Mr X to another doctor, so she could continue to help him as a "friend" rather than as a patient.

The pair refused to acknowledge their relationship to the tribunal but text messages show the pair were meeting for coffee, and at one point Dr M gave Mr X flowers and champagne for his birthday, clearly indicating some kind of romance.

"The texts, too, read like texts between a girlfriend and boyfriend with one being sulky with the other," the tribunal said.

"They rather illustrate the power/influence Dr M had over this young man."

Around the same time, Mr X's grandmother caught the pair in the back seat of the doctor's car. They said they were getting guitar equipment.

The situation escalated after Mr X stayed the night at the doctor's house after babysitting.

The doctor's husband got up the next morning and later returned to the room to find the young man sitting on their bed with the doctor naked under the sheets.

It caused an argument, with Dr M taking an overdose and eventually being diagnosed with bipolar disorder.

The pair were told to stop contact, but it continued to the point where Mr X's family laid a complaint with the Medical Council.

Texts from Mr X to his sister show that Dr M wanted him to delete the messages between them - such as those showing Dr M "wheedling" Mr X to visit her. The council believed she wanted to hide their relationship but were unable to prove it to the point where a charge was laid.

When, in the middle of 2011, Dr M terminated the relationship, the impact on Mr X was devastating. He made a serious suicide attempt - not his first - and admitted to psychiatrists the relationship was making him upset.

Mr X did not give evidence to the tribunal because his psychiatrist said it would be harmful to him.

Dr M denied the relationship. Her punishment will be decided by the tribunal following submissions from lawyers.